Foreign Diseases

By Edwin I. Pilchard.

Hog cholera was eradicated from the United States in 1978, following systematic diagnosis and destruction of infected herds. Before eradication the annual cost of hog cholera exceeded $60 million, including vaccination for its control.

The United States is free from more than nine devastating diseases that make pork production far less profitable in many other countries. Foremost among these are African swine fever, hog cholera, and foot-and-mouth disease.

The list also includes swine vesicular disease, porcine babesiosis, Japanese encephalitis, Teschen disease, melioidosis, screwworm myiasis, and exotic types of vesicular stomatitis.

African swine fever is caused by strains of a virus that vary widely in their disease-producing ability.

Some strains particularly those found in parts of Africa can cause high fever; hemorrhages in the skin, and in the spleen and other internal organs; and death of nearly all infected swine. However, strains found in recent years in Southwestern Europe, Italy, Malta, South America, and the Caribbean area produce a more prolonged disease showing difficult breathing, accumulations of fluid in the body cavities, and survival of many unthrifty virus-carriers.

The virus can be transmitted readily by direct contact, contact of swine with virus-contaminated items, and the bite of certain infected soft ticks (Ornithodoros) if the virus is in the ticks.

These ticks can get African swine fever virus either by feeding directly on diseased swine, or by hatching from eggs produced by infected ticks.

There is no successful vaccine for African swine fever. Its eradication from Cuba, the Dominican Republic, Haiti, Malta, and France required the destruction and safe disposal of all swine in the affected geographical area.

The disease has persisted for many years in Africa, Portugal, and Spain, and also may exist in several countries in which past outbreaks were reported. To help reduce the threat of this disease, the United States, Canada, and Mexico assisted the Dominican Republic and Haiti in their successful African swine fever eradication campaigns, 1978-1981.

Hog cholera was eradicated from the United States in 1978, following systematic diagnosis, quarantine, destruction of infected herds, safe disposal, and cleaning and disinfection of affected premises.

Before eradication the annual cost of hog cholera exceeded $60 million, including vaccination for its control. It has been estimated that $5.1 million would be needed to eradicate even a small outbreak of hog cholera in the United States.